Learn RUBY-ON-RAILS with Real Code Examples

# config/routes.rb
Rails.application.routes.draw do
    get '/counter', to: 'counter#show'
    post '/counter/increment', to: 'counter#increment'
    post '/counter/decrement', to: 'counter#decrement'
    post '/counter/reset', to: 'counter#reset'
end

# app/controllers/counter_controller.rb
class CounterController < ApplicationController
    @@count = 0

    def show
        render html: "<h2>Counter: #{@@count}</h2>".html_safe
    end

    def increment
        @@count += 1
        redirect_to '/counter'
    end

    def decrement
        @@count -= 1
        redirect_to '/counter'
    end

    def reset
        @@count = 0
        redirect_to '/counter'
    end
end

Demonstrates a simple Rails controller and view for a counter using in-memory state (for demonstration purposes).

# config/routes.rb
Rails.application.routes.draw do
    get '/hello', to: 'hello#index'
end

# app/controllers/hello_controller.rb
class HelloController < ApplicationController
    def index
        render json: { message: 'Hello, Rails!' }
    end
end

A minimal Rails API controller returning Hello World.

# config/routes.rb
Rails.application.routes.draw do
    get '/greet', to: 'greet#index'
end

# app/controllers/greet_controller.rb
class GreetController < ApplicationController
    def index
        name = params[:name] || 'Guest'
        render json: { message: "Hello, #{name}" }
    end
end

Demonstrates using query parameters in Rails controller.

# config/routes.rb
Rails.application.routes.draw do
    get '/json', to: 'json#index'
end

# app/controllers/json_controller.rb
class JsonController < ApplicationController
    def index
        render json: { message: 'Hello, Rails JSON' }
    end
end

Return JSON response from Rails controller.

# config/routes.rb
Rails.application.routes.draw do
    post '/form', to: 'form#submit'
end

# app/controllers/form_controller.rb
class FormController < ApplicationController
    def submit
        name = params[:name]
        render json: { message: "Hello, #{name}" }
    end
end

Handle POST requests with form parameters in Rails.

# config/routes.rb
Rails.application.routes.draw do
    get '/user/:id', to: 'user#show'
end

# app/controllers/user_controller.rb
class UserController < ApplicationController
    def show
        id = params[:id]
        render json: { user_id: id }
    end
end

Use path parameters in Rails routes.

# config/routes.rb
Rails.application.routes.draw do
    get '/error', to: 'error#index'
end

# app/controllers/error_controller.rb
class ErrorController < ApplicationController
    def index
        raise 'This is an error'
    rescue => e
        render json: { error: e.message }, status: 400
    end
end

Demonstrates basic exception handling in Rails controller.

# config/routes.rb
Rails.application.routes.draw do
    get '/redirect', to: 'redirect#index'
    get '/counter', to: 'counter#show'
end

# app/controllers/redirect_controller.rb
class RedirectController < ApplicationController
    def index
        redirect_to '/counter'
    end
end

Redirect request to another route in Rails controller.

# config/routes.rb
Rails.application.routes.draw do
    get '/', to: 'home#index'
    get '/about', to: 'home#about'
end

# app/controllers/home_controller.rb
class HomeController < ApplicationController
    def index
        render plain: 'Home'
    end

    def about
        render plain: 'About'
    end
end

Handle multiple routes in a single Rails application.

# app/services/counter_service.rb
class CounterService
    @@count = 0
    def self.get_count
        @@count
    end
    def self.increment
        @@count += 1
    end
    def self.reset
        @@count = 0
    end
end

# app/controllers/counter_controller.rb
class CounterController < ApplicationController
    def show
        render json: { count: CounterService.get_count }
    end
    def increment
        CounterService.increment
        redirect_to '/counter'
    end
    def reset
        CounterService.reset
        redirect_to '/counter'
    end
end

Use a service object to manage counter state.